Adjustable electromagnetic type slug holder in high speed chain printer



May 7, 1968 T. P. FOLEY 3,381,611

ADJUSTABLE ELECTROMAGNETIC TYPE SLUG HOLDER IN HIGH SPEED CHAIN PRINTER Filed Nov. 7, 1966 mjl INVENTOR 77/0/45 R /-24 ATTORNEY United States Patent 3,381,611 ADJUSTABLE ELECTROMAGNETIQ TYPE SLUG HOLDER IN HIGH SPEED CHAIN PRINTER Thomas P. Foley, Huntington, N.Y., assignor to Potter Instrument Company, Inc., Plainview, N.Y., a corporation of New York Filed Nov. 7, 1966, Ser. No. 592,537 6 Claims. (Cl. 101-93) ABSTRACT OF THE DISCLGSURE The specification and drawings disclose a chain printer in which an electromagnet holds the type against a backup bar The present invention, generally, relates to high speed printer apparatus and, more particularly, to a new and improved chain type high speed printer.

This invention is an improvement on co-pending patent application Ser. No. 509,501, filed Nov. 24, 1965, entitled, High Speed Printers, and assigned to the same assignee as the present invention.

With a chain type printer such as disclosed in the above referred to application, it is required to have a back-up bar means positioned relative to the type carrier to sup port the type during impact by the printing hammer. It has been suggested to include a permanent magnet as an integral part of such a back-up bar means to maintain the printing type in close sliding engagement with the backup her means. Otherwise, small spaces develop between the type and the back-up bar means, and during printing, the paper is smudged or double characters are printed because of the rebound of the type. Since the permanent magnet is behind the type carrier and is incorporated within the back-up bar means, it is not accessible for a djustment, and if it were accessible, the only adjustment that could be made is in position.

'Accordingly, it is a principal object of this invention to provide an electromagnetic structure as a part of the back-up bar means to permit ready adjustment of the strength of the magnetic field.

It is also an object of the present invention to provide a new and improved chain type high speed printer having an additional element of control over variations in position of the moving printing type.

Briefly, a high speed printer apparatus constructed in accordance with the principles of the present invention includes a printer type carrier of the chain type having means to move printing type past a printing line. A plurality of printing type is supported by the type carrier for movement along the printing line, .and a printing hammer is positioned adjacent the printing line and includes a head for impact printing and including appropriate control circuitry to operate the hammer when a predetermined one of .the printing type is in a printing position. A backup bar in accordance with the invention is positioned rela tive to the type carrier to support the printing type during impact by the hammer head, and an electromagnet is positioned to develop a predetermined magnetic field for maintaining the type in a predetermined position relative to the back-up bar.

The invention further resides in certain novel features of parts, and further objects and advantages thereof will become apparent to those skilled in the art to which it pertains from the following description of the presently preferred embodiment described with respect to the accompanying drawings in which similar reference characters represent corresponding parts in the several views, in which:

3,381,611 Patented May 7, 1968 FIG. 1 is a diagrammatic view in cross section illustrating the principal features of the present invention,

FIG. 2 is a plan view diagrammatically illustrating a modification of the invention, and

(FIG. ,3 is a wiring diagram of a switch as a modification for that shown in FIG. 2.

Referring now to FIGS. 1 and 2 of the drawings, the numeral 10 identifies, generally, a printing type carrier and a printing type 11 of a suitable magnetic material such as steel supported thereon with a raised character 12 for impact printing in the usual manner. Such a type carrier and printing type is of the form disclosed in copending patent application Ser. No. 509,501, filed Nov. 24, 1965, entitled, High Speed Printers, and assigned to the same assignee as the present invention. The numeral 1'3 refers to interleaved paper and carbon on which printing is to be effected.

A printing hammer 14 having a head 15 is pivotable about an axis 1-6 so that the head 15 may strike the paper 13 driving it against the printing type 1 1 to imprint the raised character 12 on the paper. An electromagnetic actuator 17 with a suitable winding 18 and control circuitry 19 actuate the hammer 1-4 when a desired printing type 1 1 is in position for printing.

A back-up bar 20 of a suitable magnetic material such as steel is positioned on the opposite side of the type carrier 10 from the printing hammer 14 so that the printing type I I is supported by the surfaces 21 and 22 during impact. The type carrier 10 is movable along a p'rin'ting line in the position of the paper 13 in a direction perpendicular to the view shown in FIG. 1.

The problem which the present invention solves is the tendency of the printing type III to move away from the surfaces 21 and 22. This is accomplished, in accordance with the principles of the present invention by positioning turns of electrical wire around the back-up b'ar means 20 as indicated by the numeral 23. While the direction of the winding may be any suitable direction to accomplish the desired purpose, it is shown in FIGS. 1 and 2 as extending axially along the length of the back-up bar 20. This develops magnetic lines of flux indicated by the numeral 24 through the printing type I I to provide an attraction force dependent directly upon the magnitude of the electric current flowing in the winding.

Electric current is obtained from a D-C source 25 connected directly through an off-on switch 26 and a rheostat 27 to the winding 23.

Upon closing the switch 26, an electric current flows in the winding 23, and its magnitude is adjusted by the rheostat 27 while the high speed printer is in operation. This permits the magnitude of the magnetic flux 24 to be adjusted to a value just sufiicient to maintain the printing type 11 in sliding contact with the surfaces 21 and 22 but without the attraction force being so great that excessive we'ar develops. Advantageously, the switch 26 may be coupled to the control circuitry 19 in a suitable manner known in the art as indicated schematically by the dotted line 26 so that the switch 26 is open during intervals when the type carrier 10 is moving but the printer is not required to print. In this manner, wear may be reduced.

iln FIG. 2, two spaced apart sprocket wheels 28 and 29 illustrate one form of support for the type carrier 10, which is described in greater detail in the above identified co-pending patent application Ser. No. 509,5(l1. Also, this tfigure shows a plurality of printing ha'm'mers 14 arranged side by side along a printing line indicated generally by a sp'ace 30 between the hammers 14 and the printing type 1 1.

A reversing switch is identified generally by the reference numeral 31. While the switch is normally closed in the upward direction as indicated by the dotted line 32,

a the switch 311 permits a momentary reversal of the polarity of the D-C source 25 in the event that a build up of residual magnetism within the back-up bar 20 is detected. With the connections of this switch 3-1 as shown, the same current fiow will be developed in the reverse direction as that which flows normally.

in the event that a momentary reversal of the normal current flow is not sufiicient to dislodge the residual magnetism, a connection arrangement of the switch 31 may be made as shown in FIG. 3. By this arrangement, the current limiting efliects of the rheostat 27 is eliminated during the momentary reversal of the D-C source. This will give a stronger build up of magnetic flux in the reverse direction which, in some instances, may be more desirable for the brief duration that the switch 31 is reversed.

While there has been shown and described and pointed out the fundamental novel features of the invention as applied to a preferred embodiment, it will be understood that various omissions and substitutions and changes in the form and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention. It is the intention, therefore, to be limited only as indicated by the scope of the following claims.

What is claimed is:

1. In a high speed printer apparatus having:

a printing type carrier of the chain type including means to move printing type past a printing line,

a plurality of printing type supported by said type carrier for movement along said printing line, at least one printing hammer means including a head for impact printing and including control circuitry to operate the hammer means when a predetermined one of said printing type is in a printing position, and

a back-up bar means positioned relative to the type carrier to support the type during impact by said hammer head,

said back-up b'ar means comprising:

a surface along said printing line to support the type during impact,

electromagnetic means positioned to develop a magnetic field for maintaining said type against said surface, and

means for varying the strength of said magnetic tield in order to vary the force with which said type is held against said surface.

2. In a high speed printer apparatus as set forth in claim 1 wherein:

a plurality of printing hammer means are arranged along said printing line,

said back-up bar means is elongated along said printing line, and

said electromagnetic means includes a coil in magnetic field applying relationship with said back-up bar means.

3. In a high speed printer apparatus as set forth in claim 1, wherein said means for varying the strength of the magnetic field include:

a source of direct current, and

a rheostalt means connected in current limiting relationship with said direct current source whereby the magnitude of the magnetism developed by said electromagnetic means is adjustable.

4. In a high speed printer apparatus as set forth in claim 3, including:

a reversing switch connected intermediate said electromagnet and said source of direct current to reverse the direction of current flow in the electromagnetic means.

5. In a high speed printer apparatus as set forth in claim 1, wherein:

said back-up bar means is elongated along said pr nti g line to support a plurality of printing type in sliding engagement,

electrical coil means in magnetic field applying relationship with said back-up bar means,

a plurality of printing hammer means each having hammer heads positioned along said printing line for impact printing with predetermined ones of said printing type, and

rheostat cont-r01 means connected with said electrical coil means to control the electric current flow to develop a predetermined magnetic field for maintaining said printing type in said sliding engagement with the back-up bar means.

6. In a high speed printer apparatus as in claim 3 further including:

means to decouple said direct current source from said coil during intervals when said type carrier is moving but the printer is not required to print.

References Cited UNITED STATES PATENTS 11,531,492 3/1925 Marquardt 101-382 X 11,939,681 12/1933 Fleming 101-382 X 2,092,927 9/ 1937 Merwitz 335-289 2,788,743 4/1957 Schwerin 101--382 3,017,545 1/-1962 Meier 101-382'X 3,097,598 7/1963 Hotop et a1. 10 1--378 3,144,821 8/1964 Drejza 10193 3,219,888 11 1/1965 Waring 335290 6,282,205 11/1966 Cogar 101-93 B. PENN, Primary Examiner. 

